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Designing scalable and distributed systems is a critical skill for software engineers building high-performance applications. A key principle is to break the system into smaller, loosely coupled services that can scale independently. The microservices architecture pattern embodies this, with each service having its own data store and communicating via lightweight APIs.
To handle massive throughput, event-driven architectures using message queues enable asynchronous processing. When a user places an order on Amazon, rather than blocking while fulfillment occurs, a message is published to a queue. Separate consumer services then process the message, allowing the order placement to complete quickly.
Caching frequently accessed data in memory using tools like Redis avoids repeated expensive queries. Sharding data across multiple database instances improves read and write performance. NoSQL databases provide flexible schemas and horizontal scalability for unstructured data.
Redundancy and geographic distribution enhance availability and fault tolerance. Netflix runs across multiple AWS availability zones so issues in one zone don’t take down the whole system. Automated deployment and orchestration with technologies like Kubernetes enable agility as systems scale.
Careful monitoring of key metrics like latency and error rates is essential. Techniques like load shedding, circuit breakers, and autoscaling help systems gracefully handle spiky traffic and faults. With thoughtful design, complex systems can scale to handle millions of concurrent users.